Pseudovirus Service

Q: What is a pseudovirus?

A pseudovirus is a viral particle that can mimic viral entry and replicate only once. It is not considered a live virus.

Q: Why use a pseudovirus to study COVID-19?

Neutralization methods that use live SARS-CoV-2 require working under strict bio-containment conditions in biosafety level-3 (BSL-3) laboratories. These type of facilities are rare and expensive to operate. Using a SARS-CoV-2 pseudovirus, which can be handled at BSL2, is a more affordable, safe, and accessible option.

Q: How can this pseudovirus be used to study SARS-CoV-2 neutralization?

The Spike-ACE2 interaction is a critical step to SARS-CoV-2 entry into host cells. Any molecule (e.g., peptides, antibodies, small molecules) that inhibits this protein interaction will result in reduced luminescence of the cell-of-interest compared to the positive control where no molecule is added.

RayBiotech's COVID-19 pseudovirus service enables the study of the SARS-CoV-2 virus in cell culture. This service is ideal for:

Screening patient serum for neutralizing antibodies.
Validating inhibitors of the Spike-ACE2 interaction.
COVID-19 vaccine development.

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COVID-19 Pseudovirus Service Description

Pseudovirus

Expresses the SARS-CoV-2 spike protein.

Sample types

Serum / Plasma / Peptides / Proteins / Purified antibodies / Small molecules.

Sample amount to send

Undiluted serum or plasma (100 µL) / Peptides (≥ 200 µg) / Proteins (≥ 25 µg) / Purified antibodies (≥ 20 µg) / Small molecules (≥ 1 mg).

Sample minimum

No sample minimum. We charge our service based on how many 96-well plates are required. Therefore, regardless of whether 1 well is used or all 96 wells, the charge for the service will be the same.

Replicates

We will perform 2 technical replicates unless otherwise requested.

Cell lines

You can choose between the ACE2-expressing cells, human A549 or monkey Vero. If you don't have a preference, we recommend the human A549 cell line.

Controls

Our service includes the following controls:

"Mock Infection" positive control (pseudovirus with a non-Spike glycoprotein with an ACE2-expressing cell line) at the same dilutions as your sample.
"No Sample" positive control (cell culture media with ACE2-expressing cell line).
Negative control (no pseudovirus with an ACE2-expressing cell line).

Duplicate technical replicates will be performed for all controls unless otherwise requested.

Additional negative controls with cells that do not express the ACE2 receptor, mouse NIH3T3 or ovine OFTU cells, can be added to this service upon request (additional fees apply). If you don't have a preference, we recommend the mouse NIH3T3 cell line.

Deliverables

You will receive two files:

An Excel-based report outlining the samples and their measured luminescence values. These values have already had background signal subtracted from them. The background signal is obtained from duplicate technical replicates of similar cells that have not had pseudovirus incubated with them. The Excel file will also include the inhibition rate(s) of the sample(s) at different dilutions compared to the "No Sample" positive control.
A Word document summarizing the service background, controls, procedure, and references.

How It Works

In the presence of Spike-ACE2 inhibitors, the level of luminescence will decrease.

Neutralization analysis by SARS-CoV-2-S-driven entry

Pseudoviruses expressing a non-Spike glycoprotein ("glycoprotein") or the SARS-CoV-2 Spike protein on the surface were incubated with A549 cells expressing the ACE2 receptor ("ACE2 cell") or NIH3T3 cells not expressing the ACE2 receptor ("Non-ACE2 cell"). Serum containing a neutralizing antibody was added at 400-, 200-, or 100-fold dilutions. Luminescence reflecting viral entry was measured, and the average luminescence across three independent experiments relative to the "no serum" sample data is shown. Error bars indicate standard deviations.

Western blot analysis for VSV-G and SARS-CVO2-spike

10% SDS-PAGE
Anti-VSV-G: Kerafast
EB0010 (1: 2000)

8% SDS-PAGE
Anti-S1RBD: Raybiotech
130-10808 (1:2000)

Goat anti mouse IgG-HRP: 1:5000.
Lane: 1: Pseudovirus/VSV-G; 2: Pseudovirus/SARS-COV-2-Spike

Features

Complete. Send us your samples, we'll send you results!
Fast Turnaround. 4 weeks, with an option to expedite the service (additional fees apply).
Customized. Tailored to meet your needs.
Competitive Prices. The more samples you send for analysis, the more you save.

Frequently Asked Questions

Still have questions?

What is a pseudovirus?

Why use a pseudovirus to study COVID-19?

How does this pseudovirus work?

Our pseudovirus expresses the SARS-CoV-2 Spike protein on the surface while a plasmid encoding for luciferase is contained inside the particle. No other nucleic acid is present inside the pseudovirus. The Spike protein will bind to the ACE2 receptor, the membranes of the viral particle and cell will fuse, and the plasmid will be released into the cell where luciferase will be expressed. In the presence of a luciferase substrate, cells that have been successfully infected with the pseudovirus will luminescence. See "How It Works" figure (above).

How can this pseudovirus be used to study SARS-CoV-2 neutralization?

Can I use this pseudovirus to screen for potential inhibitors of the Spike-ACE2 interaction?

Yes. However, if you have a large library of potential inhibitors or samples that you want to screen, you may want to consider using our plate-based COVID-19 Spike-ACE2 Binding Assay Kit. Hundreds to thousands of different samples can be screened rapidly and affordably. Molecules that are identified as inhibitors with the plate-based, in vitro assay can then be analyzed with our pseudovirus service. Please note that, as these are different experimental platforms, the results from the in vitro, plate-based assay may not match the results obtained with the pseudovirus service, and vice versa.

Related Categories

COVID-19 Binding Assays

COVID-19 binding assays enable rapid, high throughput, and in vitro screening of potential inhibitors of Spike-receptor complexes that facilitate SARS-CoV-2 viral entry.

Patient Samples

Different sample types from COVID-19 diagnosed patients and COVID-19 vaccinated patients, including serum/plasma, PBMCs, dried blood spots, & more.

Small Molecules

RayBiotech offers a large catalog of over 8,000 high-quality small molecules, natural or artificial organic compounds that are < 900 daltons, that can be used to study cell signaling pathways